While the site remains a mystery for many, The Mail found one non-Scientologist who has seen the "alien space cathedral," Tim Gallagos, a Las Vegas Sheriff's Department officer in the 1990s.

Gallagos said the lair contains machines to copy the works of Hubbard to share post-Armageddon and described the vault as a "giant time capsule" where all the scriptures were being kept. He said there was a one-bedroom house near the vault but it had no technology, adding he "wouldn't want to live there.

"I was suspicious of it, the whole thing," he said of the guided tour he went on in the '90s. "It did feel like they were hiding something. I wasn't allowed to go into certain areas. I know when people are lying to me, I can tell from their body language and voice they were concealing something."